Spec Mammalia: Cancridontia
INTRODUCTION The fauna of Specworld seems to revel in creations that exceed or contradict the expectations of human explorers. During the Mesozoic Era, the mammals had never achieved a body-mass of above a few kilograms, nor had they made any inroads into marine habitats. It was thus reasonable to assume that, in the absence of a K-T mass extinction event, large marine mammals ought not to exist on Spec, at all. So, when the beach-washed carcasses of multi-ton mammals were discovered in the first year of spexploration, there were gasps aplenty. It soon became clear that the carcasses belonged giant ocean-going monotremes, distant marine cousins of the platypus and echidna. As more and more species were discovered in the oceans of Spec, they were placed within a newly formed grouping, the Cancridontia or "crab-toothed" animals. Clade Cancridontia contains of over 30 species of large sea-mammals, ranging in size from less than a kilogram to over 7 tonnes. They are divided into 3 subgroups, the terrestrial and enigmatic rekes (Rekeidae), the smooches (Labiotherioidea) which come ashore to breed, and the giant walducks (Anatocetacea), which spend their entire lives at sea. Notable cancridont features include a reduced pelvic girdle (including the loss of the epipubic bone), a flattened paddle or fluke-like tail in the marine species, and a pair of venomous spurs on the hindquarters that can pivot into slots in the flesh when not in use. The leathery monotreme-bill is packed with electrosensors that provide a similar function to a shark's ampullae of Lorenzini, allowing the mammal to detect the minute electrical nerve-impulses of both their predators and prey. As with other monotremes, the distal end of the digestive, reproductory and excretory systems all converge at a single cloacal vent. It is their bizarre dentition that truly sets them apart from other mammals. Walducks and their relatives have three sets of bunodont molars on each jaw, with each tooth bearing a single, longitudinal row of 2-4 rounded cusps that give the tooth the appearance of the inner surface of a large crab-claw. The males of some species also possess a pair of tusk-like lower teeth that are believed to be premolars. BIOLOGY The cancridont reproductive process is unique among monotremes in that, instead of laying eggs, mothers give birth to a single, fully-developed baby. A look inside a pregnant walduck reveals the key to this strategy - they have developed a eutherian-like chorioallantoic placenta. This may not be as ground-breaking as it sounds as placentae have evolved multiple times among mammals (not to mention fish and reptiles). Crude versions of this structure have arisen at least twice in Home Earth's Australian marsupials and several times among Spec's metatheres. However, the cancridonts are the only mammals outside the eutheria to have fully refined the placenta, thus allowing it to sustain a foetus within the mother's body during a lengthy gestation period. The capillaries of the mother become fully linked with those of the placenta, bringing nourishment to the growing baby while eliminating wastes. As with other monotremes, however, mother cancridonts lack nipples. Smooches feed their offspring in the conventional monotreme way by secreting milk from patches of skin. Walducks producing a viscous lactation that clings to their ventral surface as a slimy film which is scraped or pecked off by the young. HISTORY The fossil record of the clade, which extends as far back as the early Miocene, is scrappy and is still in the process of being described. It includes material from New Zealand, South America and the sub-Antarctic Islands. Even the oldest known fossil forms conform closely with modern families and it seems clear that their evolutionary history goes back much further. Based on their current and fossil distribution, the group appeared in the south polar regions during the early Cenozoic (perhaps on mainland Antarctica itself). Their evolution was possibly spurred on by the chilling of the southern oceans towards the end of the Eocene that would have been to the detriment of non-mammalian competitors, like mosasaurs. One intriguing Mesozoic jaw-fossil is Kollikodon, an Early Cretaceous Australian monotreme that possessed similar rounded cusps to those of walducks (although arranged in a more conventional double rather than single row). Drawing a relationship between walducks and Kollikodon is tempting but is difficult to prove in the absence of fossil postcrania from the latter. REKEIDAE (Waitoreke & Kaureke) Waitoreke (Reke montanus) When first discovered on Spec's island of Aotearoa, the waitoreke, one of only two species in the family Rekeidae, was classified as an ornithorynchid. The creature, which did outwardly resemble a homely platypus, did not receive much scientific interest as, other than its odd choice of habitat far from its presumed Australian homeland, it did not seem to differ much from its Home-Earth counterpart. The waitoreke languished under this mistaken pedigree for years, until spexplorers, in pursuit of the cryptic kaureke, found out the truth. Kaureke (Reke morrisi) Detailed anatomical study of the kaureke, and later the waitoreke, revealed that their ancestors did not, in fact, come from Australia. Rather, the early rekes were Antarctic, otter-like marine fish-eaters, the progenitors of the whale-like walducks. These creatures must have spread from Antarctica during the middle Cenozoic, some coming to rest on the Aotearoa. These two islands, recently blasted clean of native mammal fauna by volcanic upheavals, offered little resistance to the early rekes as they spread and diversified. As their ocean-going relatives went extinct, to be replaced by the more highly derived smoochers and walduks, Aotearoa became a refuge for the last surviving rekes. At up to 90 centimeters in length, the waitoreke is one of only two species of terrestrial mammal present on the Aotearoan archipelago. Its body resembles that of a platypus, though unusually plump and truncated, probably an adaptation for retaining body-heat in the cool climes that the creature inhabits. The bill is particularly large and spatulate, and bears anterior false keratinous teeth. Near the back of the mouth, the waitoreke possesses a few true teeth, these clearly bunodont. So specialized for its platypus-like lifestyle is the waitoreke, however, that little evidence remains of its true nature. The hindlimbs are underdeveloped, but the pelvic girdle is robust and functional. Only the waitoreke's dentition, along with the unique maneuverable spurs on the hind legs of both sexes, demonstrate the waitoreke's cancridont affinities.  The waitoreke is found on both of the main Aotearoan islands and on a number of outliers including Stewart Island. Strangely, it appears to be restricted to upland habitats on the North Island but can be seen both in the mountains and at near sea-level in the south.  Waitorekes are secretive creatures that are usually found near flowing fresh water and are especially at home in cool montane streams. They are however, not as aquatic as some of their cousins, foraging for food both in the water and along the riverbank. Their powerful forelimbs augment the already impressive digging abilities of their spoon-like bill allowing, them to produce elaborate tunnels. They have been known to feed on a variety of lizards, frogs and large insects on land, and are sporadically active during winter, allowing them to dig up torpid prey.  The waitoreke’s hunting skills really come to the forte in the water however. The creature anchors itself against the current with its foreclaws while it grubs around with its bill, overturning pebbles and churning the bottom muck in its search for prey. Snails, worms, insect larvae and small fish are fair game for this adaptable mammal.  Like other cancridonts and most of Aotearoa’s herpetofauna (frogs and lizards) the waitoreke does not lay eggs, but instead gives birth to a pair of live, underdeveloped young that are nursed in the burrow. Long hinted at by eyewitness reports, but only recently verified as a real creature, the kaureke is a close relative of the waitoreke, though one could scarcely imagine two more different mammals. Kaurekes evolved from otter-like cancridonts that swam from Antarctic to Aotearoa perhaps 30 million years ago. These reke progenitors must have found New Zealand to be a paradise, completely devoid of mammalian competition and bursting with life of other sorts on which to feed. There must have been a great explosion of diversity in those early days, a radiation that produced not only the relatively conservative waitoreke, but also fully terrestrial forms like the burrowing kaureke. In the intervening millennia, New Zealand's chronic volcanic spasms have destroyed the remainder of the islands' mammalian diversity, leaving the waitoreke and the kaureke as the last survivors of this clade. The kaureke is toothless, though the young (born live as with other cancridonts) possess bunodont teeth at the back of their mouths. The pelvis and hind legs are reduced, and the forelimbs are greatly enlarged to serve as shovels. The kaureke's eyes are also small, and this burrower hunts worms and insects mostly by smell and electro-sense. Found only in the deep forests of the South Island, kaurekes were long undiscovered and only recently has their existence been proven.  LABIOTHERIOIDEA Although initially considered to be the more primitive than the two cancridont subclades, recent studies have shown that these animals possess their own suite of unique adaptations that allow them to thrive in the harshest of marine environments. Smooches possess fully-functional hind limbs, a luxuriant, velvetine pelt and a life-cycle that requires them to come ashore to pup. Their most notable external feature are the muscular and mobile anterior bill-tips (the "smoocher") that resembles a pair of puckering human lips. This structure creates a tight seal that allows the animal to generate over 1 negative atmosphere of suction when underwater. With this ability, a smooch can easily pluck a limpet off a rock or suck a clam right out of its shell. Paired valves in the roof of the mouth allow the nostrils to expel the excess water from this activity. CRYITHERIIDAE (Creakers) This archaic family of labiotheres contains just two living species, both of which dwell south of the Antarctic convergence. The smoocher is small and comparatively poorly developed while both sexes possess a pair of tusk-like premolars. Creakers feed on a wide variety of hard-shelled benthic prey. They are highly territorial animals that form monogamous pair-bonds and continually advertise their territories with a monotonous groaning-call that is akin to the sound of someone walking over old-wooden floorboards. This hefty creature has the southernmost distribution of any Spec-mammal and is the only one to regularly come ashore on the Antarctic ice. It is a most extraordinary-looking beastie with it's long plump body and tusked, duck-bill. Two retractable five-inch blades are set in the hindlimbs that can inject a potent venom. Creaker hindquarters are capable of a surprising degree of lateral movement for a mammal, allowing the blades to be brought to bear against threats to the animal's flanks. Antarctic Creaker (Cryotherium mawsoni) Creakers spend most of their time foraging on the benthos off the Antarctic coast. Beneath a depth of 15m, beyond the influence of the abrasive pack-ice, there is a rich variety of prey. The creakers seek out hard-shelled invertebrates with their sensitive bills amongst the dropstone-littered seabed, including limpets, clams, isopods and pycnogonids. These either sucked into the maw or simply grabbed before being crunched up with their large molars. Creakers are the only Antarctic tetrapods that utilize this rich resource, but it comes at a price. In the frigid south polar waters, the creakers' favored prey grow exceedingly slowly with population doubling-times of well over a decade. The creakers are thus very sparsely distributed with pairs of mated-adults claiming a territory of several square kilometers - to exist in more dense concentrations would soon result in the seafloor being stripped bare. These territories (which have to be moved with the seasonal ebb and flow of the pack-ice) are vigorously defended upon hearing the groans of an intruding creaker and can lead to violent confrontations. When foraging, the creakers never stay in one spot for long, taking a little from here-and-there. Depending on how good the feeding has been, a creaker pair produces a pup every 1-3 years. The females give birth during the austral summer when the retreat of the pack-ice leads to rich pickings in the shallows. They will happily pup on either ice or exposed rock, giving birth to a single kg baby that grows rapidly on a rich, fatty milk. During the six weeks prior to weaning, the mother stays ashore with the child while the father continues to forage and patrol, occasionally bringing food back to his mate. Infant mortality is low with over 75% of offspring reaching adolescence. They remain with their parents for up to a year after which they are driven off to find partners and start their own territories. LABIOTHERIIDAE (Smooches) About ten species of these enchanting creatures can be found in shallow, temperate and subtropical seas throughout the Southern Hemisphere. Additionally, three small species are to be found in the tropical waters off the Hawaiian Islands, the Gulf of Mexico and the Caribbean. Unlike their more southerly creaker cousins, the labiotheriids lack tusks and have a far more gregarious lifestyle. The smoocher is very wide and prominent, with different species possessing a different lip-configuration, each optimized for a specific kind of prey. Wide-mouth smooches are polygamous harem-breeders, coming ashore in their hundreds to pup and mate. Only males have fully-developed spurs, and their poison is considerably less toxic than those of the creakers. They employ these spurs in battles used to establish a breeding hierarchy during the mating season. Tasman Smooch (Labiotherium tasmaniensis) This is a common species throughout much of the western South American coast. It is found from Tierra del Fuego to the Juan Fernandez islands where it forages in the sand for large oysters and clams. It communicates with a series of high-pitched squeals that advertise its presence long before it can be seen in the turgid waters. ANATOCETACEA The Anatocetacea form a diverse but enigmatic array of pelagic mammals. They are distinguished from their smooch brethren by their hairless, fishlike bodies and the absence of fleshy, mobile lips. The hind limbs that have been almost completely lost - all that remain are a pair retractable venom-spurs that are present in juvenile animals, but which are absorbed and lost shortly after weaning. Magellan Smooch (Anatophoca punctatum) Anatocetes can be found throughout the world's open-oceans but are rarely sighted owing to their deep-diving habits with little time spent at the surface. Their stronghold appears to be the Antarctic and Sub-Antarctic where more than half of the species can be found, becoming increasingly sparse in warmer waters that is the stronghold of their reptilian competitors, the saurocetes. The Magellan Smooch being one such example. PELAGANSERIDAE (Walducks) Spotfin Walduck (Pelaganserus chirurgus) The walducks are sleek, fast-moving animals that prey on similarly sleek and fast-moving pelagic squid and belemnoids. For all effective purposes, the pelaganserids appear to be Specworld's answer to the ziphiid beaked-whales of Home-Earth, a remarkable example of convergent evolution. Like ziphiids, they capture their prey by means of suction, a capability that gives them a vital advantage over penguins and mosasaurs, which must physically grab their prey. This gregarious species is one of the more common walducks. Offshore sightings of pods of up to 30 animals have been widely reported across the temperate Southern Hemisphere. It appears to feed almost exclusively on mesopelagic squid. The species name, meaning "surgeon" refers to the scalpel-like blades found on juvenile animals. Moby Duck (Pelaganserus folkensi) While the south may have the most species, it is in the northern hemisphere where we find the largest walduck and the largest mammal on Spec. The strikingly bicolored Moby Duck is restricted to the temperate and sub-arctic North Pacific, it has been sighted amongst drift ice in the Sea of Okhotsk. It is a deep-water species, sometimes diving to a depth of over 3 kilometers where it takes squid of up to 2 meters in length. Little is known about its habits. It has been sighted as a solitary individuals or in aggregations of over 20 animals. SPHYRNATHERIIDAE (Wingheads) These bizarre creatures are amongst rarest and least known of all Spec mammals and have never been observed as healthy animals in their natural habitat. All that we currently have are a series of beach-washed carcasses or stranded animals on the brink of death. They have compact, robust body-forms, quite unlike the graceful lines of the true walducks, which suggests that they are comparatively slow swimmers. Sphyrnatheriids are instantly recognizable by the large, leathery wing-like projections from their upper and lower beaks. Precisely what function these structures serve is unknown, the most likely explanation is that they greatly enhance the field of electrosensor coverage, giving it a full three-sixty degree view of all electrical activity in its vicinity. If these wings do indeed provide an electrosensory early-warning function, it may explain why scientists have never been able to get close to one in the wild since the creatures would be given ample warning of approaching vessels. Pacific Winghead (Sphyrantherium pacificus) Currently the best known of the wingheads with over ten specimens in collections. Recorded stomach contents have included squid-beaks, small ammonites, benthic fish and salps suggesting a fairly generalized diet. ---- - Brian Choo and Daniel Bensen ---- ,=R. montanus (Waitoreke) ,=Rekeidae=Reke=| | `=R. morrisi (Kaureke) | | ,=Cryotheriidae=Cryotherium mawsoni (Antarctic Creaker) | ,=Labiotheroidea=| | | | ,=Labiotherium tasmaniensis (Tasmanian smooch) | | `=Labiotheriidae=| | | `=Anatophoca punctatum (Magellan smooch) =Cancridontia=| | `=| | ,=P. chirurgus (Spotfin walduk) | ,=Pelaganseridae=Pelaganserus=| | | `=P. folkensi (Moby Duck) `=Anatocetacea=| `=Sphyrnatheriidae=Sphyrnatherium pacificus=(Pacific Winghead) Category:Spec Dinosauria Category:Animals Category:Mammals Category:Alternative evolution Category:Pacific Ocean Category:Antarctica Category:Monotremes Category:New Zealand Category:Aquatic Creatures Category:South America Category:Carnivores